Fackenheim researched the relationship of the Jews with God, believing that the Holocaust must be understood as an imperative requiring Jews to carry on Jewish existence and the survival of the State of Israel. He emigrated to Israel in 1984.

Emil Fackenheim created this concept and advocated it as what he believed to be the "614th commandment" or "614th mitzvah." The "614th Commandment" can be interpreted as a moral imperative that Jews not use the facts of the Holocaust to give up on God, Judaism or - in the case of secular Jews as well - on the continuing survival of the Jewish people, thereby giving Hitler a "posthumous victory". The meaning of this imperative has been the subject of serious dialogue both within and beyond the Jewish community. Opposition to the goals of Hitler is a moral touchstone that has implications for several sensitive issues.

Traditional Jewish law contains 613 mitzvot (commandments) as compiled by Maimonides. These laws–365 of which are negative (e.g. "Thou shalt not...") and 248 of which are positive–cover all aspects of life. Fackenheim asserted that tradition could not anticipate the Holocaust, so one more law, a 614th Commandment, became necessary. "Thou shalt not hand Hitler posthumous victories. To despair of the God of Israel is to continue Hitler's work for him."[6] This proposes that people of Jewish heritage have a moral obligation to observe their faith and thus frustrate Hitler's goal of eliminating Judaism from the earth. Perhaps it could be added that the evil inclination and also Amalek's work should be prevented.

Fackenheim came to this conclusion slowly. A professor of philosophy at the University of Toronto and a Reform rabbi, he did not become a Zionist until 1967, when his reaction to the Holocaust and its implications for Jewish law crystallized:

It was at a meeting, just before the Six Day War. It was a meeting in New York, and I had to make a speech. Before that, the Holocaust had never been essential to my ideology. However, when the chairman said, 'You've got to face it,' I had to face it. I said the most important thing I ever said.[7]

In a fuller expression of his sentiment, Fackenheim explains the concept this way:

... we are, first, commanded to survive as Jews, lest the Jewish people perish. We are commanded, secondly, to remember in our very guts and bones the martyrs of the Holocaust, lest their memory perish. We are forbidden, thirdly, to deny or despair of God, however much we may have to contend with him or with belief in him, lest Judaism perish. We are forbidden, finally, to despair of the world as the place which is to become the kingdom of God, lest we help make it a meaningless place in which God is dead or irrelevant and everything is permitted. To abandon any of these imperatives, in response to Hitler's victory at Auschwitz, would be to hand him yet other, posthumous victories.[8]

In dialogue about this subject, choice of words is a sensitive matter. Within the Jewish community, some absolutely reject Fackenheim's assertion that this could be called a commandment. Commandment 580 already forbids adding to the Torah commandments. Wording that expresses this concept in the form of a commandment may also give offense.[9]

This becomes a contentious point because references to a "614th commandment" are not unique to Fackenheim. This concise term has other shortcomings besides the theological objection. To count this as an addition to Jewish law is an implicit statement that it applies only to Jews. Opposition to the goals of Hitler is a universal concept. Gentiles can respect it by studying the Holocaust and opposing anti-Semitism. In Christian contexts this ideal sometimes appears as the "11th commandment." Christians generally recognize 10 commandments of the Old Testament. This may give unintentional offense to Jews who recognize a different 11th commandment and may lead to confusion with other unrelated ideas that Christians have called an 11th commandment. Jesus stated two commandments: "Love the Lord thy God with all thy heart, soul, mind and strength." and "Love thy neighbor as thyself."

Although there is no single formulation that expresses this concept in terms that avoid controversy, posthumous victories and Hitler appear in most descriptions.

Fackenheim applied this reasoning to the state of Israel and its Law of Return as a necessity to prevent a second Holocaust. Had a Jewish state existed in the 1930s, it could have accepted Jewish refugees and rescued large numbers of people.[10] This opinion carries clout with most Jewish people although the specifics of how to apply it in contemporary politics is a subject of debate. Boris Shusteff invokes it in a conservative opposition to Israeli withdrawal from settlements.[11]

The concept encounters broad acceptance in connection with Holocaust remembrance. In the late twentieth century, efforts to document the memories of remaining Holocaust survivors echoed the notion that preserving these facts for future generations was a way to keep Hitler and his ideas in the grave. A guide for British primary school teachers gives the concept in a guide for informing children about the Holocaust.[14] Richard A. Cohen of the University of North Carolina at Charlotte cites it in an essay, "The Holocaust is a Christian Issue."[15]

The phrase finds resonance within Christian communities as a rebuke against anti-Semitism. Methodist minister Rev. Robert A. Hill quotes Fackenheim in a sermon with this context:

...the fact is that Christianity has been pervasively guilty of latent and patent anti-Semitism and the Gospel of John has been one of its sources. We have and can learn from this failure, by carefully monitoring our use of religious language...and our Jewish brothers and sisters can teach us to continue, with Jacob, to wrestle with God.[16]

Within the broader context of religious tolerance, this concept applies to the sensitive subjects of conversion and intermarriage. Gregory Baum, a German-born Catholic theologian and Professor Emeritus in Religious Studies at McGill University in Montreal, expresses the effect of this concept on Christian views toward conversion. From the perspective of most Christian faiths, whose doctrines normally advocate conversion of nonbelievers, this represents a deep respect for Fackenheim's concept:

After Auschwitz the Christian churches no longer wish to convert the Jews. While they may not be sure of the theological grounds that dispense them from this mission, the churches have become aware that asking the Jews to become Christians is a spiritual way of blotting them out of existence and thus only reinforces the effects of the Holocaust.[17]

Fackenheim's affirmation of his Jewish heritage, although embraced by many other Holocaust survivors, was by no means universal. Physicist Lise Meitner had been born and brought up Jewish. She rejected newspaper attempts to characterize her as a Jew following the bombing of Hiroshima when the press learned that she had been the first scientist to recognize nuclear fission. Decades before Hitler rose to power she had become a Lutheran. Although the Nazis stole her savings and ruined her career she refused to work on the bomb or let Hitler define her identity.[18]

Intermarriages between Jews and non-Jews are relatively common in the United States and Canada. Several circumstances complicate these unions from the perspective of the Jewish community. Different movements within Judaism recognize different standards for conversion to Judaism and transmission of their heritage. Social pressure generally falls upon men to marry Jewish women because all movements recognize a Jewish woman's offspring as Jews.

(Note: Starting in the late 1960s, several movements in Judaism ceased recognizing Jewish women's offspring as Jews if the women intermarried. The Reconstructionist movement of the United States, followed by the Reform movement of the U.S. in 1983, declared that they would accept the children of either an intermarried Jewish father or an intermarried Jewish mother as Jews only if the children are raised as Jews. If the children are not raised as Jews, and later wish to join the Reform or Reconstructionist movements in the U.S., they must convert. The Society for Humanistic Judaism in the U.S. will accept the children based on their own self-identification. The Orthodox and Conservative movements in the U.S. still require the conversion of patrilineal [Jewish fathers] children, but accept the children of Jewish mothers, regardless of how they are raised. Jewish Renewal rabbis do not have denominational guidelines, and go on a case-by-case basis.)

A puzzling twist to this controversy is the fact, apparently not well known, that Prof. Fackenheim himself was intermarried, and the Jewishness of one of his children was rejected by an Israeli Orthodox court, even though that son was converted via Orthodox ritual as a child, and is a citizen of Israel. (See, "Rabbinical Court casts doubt on conversion of son of famed Jewish theologian" in the Jerusalem Post, January 19, 2009).

According to this news article, his wife converted to Judaism some time after the marriage. Jews using Fackenheim's admonition not to give posthumous victories to Hitler as a reason to dissuade people from intermarrying are apparently not aware that Fackenheim was himself intermarried.[19]

Rabbi Toba Spitzer finds this idea compelling yet incomplete. In a Passover essay for SocialAction.com she addresses it sympathetically before embracing the Passover tradition and its Seder ritual as a more meaningful story:

...of a people born in slavery, freed by their God, and taken on a transformational journey. It is the story of the steps taken towards becoming a community bound by a holy covenant, where social relationships are defined by the Godly principles of tzedek and chesed, justice and love.[20]

I am Jewish because my mother is Jewish, and, more importantly, because I believe Judaism is loving, just, joyous, hopeful and true. I am not Jewish, and I did not teach my children or my students to be Jewish, just to spite Hitler.[21]

The same criticism was formulated by Jewish philosopher Michael Wyschogrod in his 1971 review of God's Presence in History. Wyschogrod questioned the value of a definition of Judaism that merely inverts antisemitism into a bigoted "semitism." The uniqueness of Auschwitz as a historical event, moreover, is a dubious distinction. "It is necessary to recognize that, from any universally humanistic framework, the destruction of European Jewry is one notable chapter in the long record of man's inhumanity against man."[22]:292 Not satisfied with criticism, however, Wyschogrod offered a traditional explanation of the Jewish claim to uniqueness and chosenness formulated in positive terms.

The fate of Israel is of central concern because Israel is the elect people of God through whom God's redemptive work is done in the world. However tragic human suffering is on the human plane, what happens to Israel is directly tied to its role as that nation to which God attaches His name and through which He will redeem man. He who strikes Israel, therefore, engages himself in battle with God and it is for this reason that the history of Israel is the fulcrum of human history. The suffering of others must, therefore, be seen in the light of Israel's suffering. The travail of man is not abandoned, precisely because Israel suffers and, thereby, God's presence is drawn into human history and redemption enters the horizon of human existence.[22]:293

Focusing not on Fackenheim's conception of Jewish identity but on Zionism, renowned scholar Daniel Shoag presents a critique of this view from within the Jewish community in The Harvard Israel Review:

While Fackenheim's sentiments about the need for Jewish self-reliance in the form of a Jewish state are immensely popular, Fackenheim fails to locate a religious or divine source for his moral imperative. For Fackenheim, self-defense, and its manifestation in Zionism, are not religious values but rather things that precede religious value or stand outside of it. Thus Fackenheim locates the significance of the Jewish State in the Holocaust rather than in traditional Judaism...[23]

We abuse the Holocaust when it becomes a cudgel against others who have their claims of suffering. The Shoah must not be misused in the contest of one-downsmanship with other victims of brutality....The Shoah has become our instant raison d'etre, the short-cut answer to the penetrating questions of our children: 'Why should I not marry out of the faith? Why should I join a synagogue? Why should I support Israel? Why should I be Jewish?' We have relied on a singular imperative: 'Thou shalt not give Hitler a posthumous victory.' That answer will not work. To live in spite, to say 'no' to Hitler is a far cry from living 'yes' to Judaism.[24]

Rabbi Michael Goldberg has developed this sort of criticism in his book Why Should the Jews Survive?: Looking Past the Holocaust Toward a Jewish Future.

During Fackenheim's last interview in 2000 he confronted the question, "Do you think Israel can ever come to the point where it doesn't have to be in a state of resistance?"

I think it will be a very long time. But I would say this. Will the time ever come when we can say Hitler's shadow is gone? I think, yes, it will come when Israel is accepted in peace with its neighbor states. But it doesn't look like it will happen soon.[7]

There are few survivors of the Holocaust as of 2005[update], and many feel their memories and opinions deserve respect. The idea that people must not further Hitler's goals has become a meaningful part of public discourse about Judaism, Zionism, and anti-Semitism, but many who discuss it sympathetically do not embrace it wholeheartedly. Some in the newer generations who understand the Holocaust as history feel the injunction to grant Hitler no posthumous victories denies positive interpretations of the subjects it addresses.

The preceding discussion, rich as it is, does not begin to do justice to Fackenheim's achievements and teaching as a professor and scholar of philosophy (in his years as professor of Kantian, Hegelian, and German idealistic philosophy at the University of Toronto) — above all as a scholar of Hegel; nor does it do justice to his oft expressed indebtedness to Leo Strauss, who was for Fackenheim the exemplar of what it means for a Jew to pursue the philosophic vocation in the times in which we live.

For those who are interested in Fackenheim's contribution to the understanding of how strictly rationalist philosophizing can and must be a part of the crown of Jewish existence in our time, worth pondering is Leo Strauss's judgment that Fackenheim's book on Hegel — The Religious Dimension in Hegel's Thought (1967) — is the strongest alternative to Kojève's atheistic interpretation of Hegel.